The present invention relates to a plate lockup device position detecting apparatus for a printing press, e.g., a sheet printing press, which detects whether or not plate lockup devices are restored to their origin positions.
Conventionally, in a printing press, e.g., a sheet printing press, the leading and trailing ends of a plate are set in leading- and trailing-side plate lockup devices provided to a plate cylinder, and the plate cylinder is moved by using a plate registration remote controller, thereby adjusting plate registration. For example, a plate registering device, as disclosed in Japanese Utility Model Laid-Open No. 64-42135, having motors and screw mechanisms in the horizontal and vertical directions of a plate is operated by remote control using a plate registration remote controller, thereby adjusting the position of the plate set in the plate lockup devices.
In this adjustment, when, e.g., the position of the plate cannot be sufficiently adjusted with the adjustment width of the plate registration remote controller, the plate lockup devices are sometimes manually moved in the horizontal or vertical direction of the plate. When the plate lockup devices are moved in this manner, both the leading- and trailing-side plate lockup devices must be manually restored to their origin positions before the plate is exchanged for a new one. Especially, when an automatic plate exchange apparatus enabling automatic plate exchange is used, if the operator forgets to restore the plate lockup devices to their origin positions, exchange and registration errors may be caused.
Conventionally, however, no means is available for detecting whether or not the plate lockup devices are restored to the origin positions, and if the plate lockup devices are forgotten to be restored to their origin positions, troubles as described above sometimes occur.